The present disclosure relates to a method for identifying a state of a sample such as, for example, a blood sample, which is in a sample tube extending along a longitudinal direction, from a predetermined set of states, wherein the set of states contains an unmixed state and a mixed state.
Samples such as, for example, medical samples such as blood samples, are often filled into conventional sample tubes for the purposes of being subjected to analyses. By way of example, the presence of a disease, or an alcohol concentration, in the blood can be determined within the scope of such an analysis. Typically, many analyses require individual constituents of such a sample to be split prior to the analysis. In the process, a plurality of phases of different phase types is typically produced in the sample tube.
By way of example, the following phases, more precisely types of phases, are known in blood samples:
Air: a region, typically at the upper end of the sample tube that has not been filled by liquid or solid constituents;
Whole blood: blood with all constituents that has not been separated, as taken from a human or an animal;
Blood plasma or serum: a liquid component of the blood, remaining as a supernatant when the cellular constituents were separated from a blood sample;
Coagulum: cellular constituents of blood such as red blood cells, blood platelets and white blood cells; and/or
Gel: a substance which is largely transparent in the visible spectrum, introduced into the sample tube in addition to the blood sample in order to improve the separation. The gel is typically already filled into the sample tube by the manufacturer of the sample tube and is therefore situated at the lower edge or end of the sample tube prior to the separation steps possibly to be carried out.
After a sample tube is filled with a blood sample, the sample is initially in a mixed state, in which all constituents of the human or animal blood are contained in a single homogeneous phase. This applies at least for as long as there has not been an onset of any significant blood sedimentation. Now, prior to the analysis, the sample is intended to be transferred into an unmixed state, in which the individual constituents of the blood are present in separated phases. To this end, the sample is typically centrifuged, which can be carried out by a conventional laboratory centrifuge. Hence, in this typical case, the mixed state can be referred to as non-centrifuged state and the unmixed state can be referred to as centrifuged state.
It is to be understood that the terms non-centrifuged state or centrifuged state are often used within the scope of this application, as the method of centrifuging is the most common method for separating a sample. However, in principle, different separation methods can also be applied, and the results of these separation methods should also be comprised by the term centrifuged state. Likewise, the term non-centrifuged state should, in principle, denote a state in which a sample is without an actively performed separation step, independently of the envisaged separation method.
If an analysis to be performed on the sample requires an unmixed state, the analysis of a sample in the mixed state would lead, at least, to a distorted result of the analysis. Moreover, blockages of the lines or damage to the analysis instrument may be the consequence. Therefore, samples should only be analyzed in the unmixed state.
Until now, a manual check prior to the analysis step as to whether each individual sample is in the unmixed state was conventional. To this end, a human must observe each sample and identify whether the sample is in the unmixed state on the basis of the visible phase types. On the one hand, this is time-consuming and, on the other hand, there is also the risk of human failure, and so a sample in the mixed state may not be identified in good time under certain circumstances, for example, due to inattentiveness.
Therefore, there is a need for a method for identifying a state of a sample which allows an automated identification of the state as well as for a device for analyzing samples which applies such a method and a laboratory automation system with such a device.